#!/usr/bin/perl
use warnings;
use strict;

use Data::Dump qw(dump);
use Device::SerialPort qw(:STAT);

my $debug = $ENV{DEBUG} || 0;

my $port = Device::SerialPort->new('/dev/ttyUSB0');
$port->baudrate(9600);
$port->databits(8);
$port->parity('none');
$port->stopbits(1);
$port->handshake('none');

$port->read_char_time(500);
$port->read_const_time(1000);

sub as_hex {
	my @out;
	foreach my $str ( @_ ) {
		my $hex = uc unpack( 'H*', $str );
		$hex =~ s/(..)/$1 /g if length( $str ) > 2;
		$hex =~ s/\s+$//;
		push @out, $hex;
	}
	return join(' | ', @out);
}

sub hex2bytes {
	my $bytes;
	$bytes .= pack('C', hex('0x' . $_)) foreach split(/\s+/,join(' ',@_));
	return $bytes;
}

sub crc {
	my $data = shift;
	my $crc = 0;
	for my $i ( 0 .. length($data) - 2 ) {
		if ( $crc & 0x80 ) {
			$crc = ( $crc << 1 ) ^ 25;
		} else {
			$crc = $crc << 1;
		}
		$crc = $crc & 0xff;
		my $byte = ord(substr($data,$i,1));
		$crc = $crc ^ $byte;
#		warn "## ", as_hex(chr($byte)), " crc = ", $crc, " ", as_hex(chr($crc));
	}
	if ( chr($crc) ne substr($data,-1,1) ) {
		warn "CRC error for ",as_hex($data), " calulated ", as_hex(chr($crc));
	}
}

sub v {
	my ($hex,$desc) = @_;
	my $bytes = hex2bytes( $hex );
	warn "# $desc\n";
retry:
	warn ">> ",as_hex( $bytes );
	crc( $bytes );
	$port->write( $bytes );

	my $data = $port->read(1);
	warn "<< len: ",ord($data) if $debug;

	goto retry if ord($data) == 0;

	$data .= $port->read(ord($data) - 1);
	crc($data);
	warn "<< ",as_hex($data);

}

v '07 02 00 00 00 04 C4', "hardware version";

v '07 0A 00 00 00 04 44', 'software version';

v '07 00 01 00 06 0E EA', 'temperatures';

v '07 00 00 00 26 0A A6', 'last errros';

v '07 00 00 00 26 00 AC', 'last errros (with invalid length)';
